1. Field of the Invention
Embodiments of the present invention relate to an organic light emitting display device and a method for operating the same.
2. Discussion of the Related Art
According to a recent development of multimedia, there is an increasing demand for a flat panel display. In order to satisfy this increasing demand, various flat panel displays such as liquid crystal display, plasma display panel, and organic light emitting display are practically used. Among the various flat panel displays, the organic light emitting display device has attracted significant interest as a next-generation flat panel display owing to the advantages of rapid response speed and low power consumption provided by such displays. In addition, the organic light emitting display device can emit light in itself, whereby the organic light emitting display device does not cause a problem related with a narrow viewing angle.
Generally, the organic light emitting display device according to the related art may include a display panel having a plurality of pixels, and a panel driver for driving each of the pixels. In this case, each pixel is formed in a pixel region which is defined by the crossings of each of the plurality of gate lines and each of the plurality of data lines.
As shown in FIG. 1, each pixel may include a switching transistor ST, a driving transistor DT, a capacitor Cst, and an light emitting device OLED.
The switching transistor ST is switched by a gate signal GS supplied to a gate line G, thereby supplying a data voltage Vdata, which is supplied to a data line D, to the driving transistor DT.
The driving transistor DT is switched by the data voltage Vdata supplied from the switching transistor ST, thereby controlling a data current Ioled flowing from a driving power source VDD to the light emitting device OLED.
The capacitor Cst is connected between gate and source terminals of the driving transistor DT. The capacitor Cst stores a voltage corresponding to the data voltage Vdata supplied to the gate terminal of the driving transistor DT, and turns-on the driving transistor DT by the use of stored voltage.
The light emitting device OLED is electrically connected between a cathode source VSS and the source terminal of the driving transistor DT. The light emitting device OLED emits light due to the data current Ioled supplied from the driving transistor DT.
Accordingly, in the related art, as the driving transistor DT is switched by the data voltage Vdata, a level of the data current Ioled flowing from the driving power source VDD to the light emitting device OLED is controlled in each pixel of the organic light emitting display device and consequently the light emitting device OLED emits light, thereby displaying a predetermined image.
However, in the case of an organic light emitting display device according to the related art, the characteristics of the driving transistor DT (for example, threshold voltage Vth/mobility) may be different for each pixel due to non-uniformity in the process of manufacturing the thin film transistors used. Accordingly, even though the data voltage Vdata is identically applied to each pixel of the organic light emitting display device according to the related art, it is difficult to realize uniform picture quality due to a deviation of the current flowing in the light emitting device OLEDs.